Woods A M, Queen J S, Lawson D
Department of Anesthesiology, University of Virginia Health Sciences Center, Charlottesville 22908.
Anesth Analg. 1991 Dec;73(6):765-71. doi: 10.1213/00000539-199112000-00015.
Strenuous expulsive efforts involving sequential Valsalva maneuvers may result in maternal hypoxemia during the second stage of labor. Pulse oximetry has been used to assess oxygen saturation in laboring parturients, and this study was undertaken to evaluate the performance of the pulse oximeter (Nellcor) during the Valsalva maneuver. In both pregnant patients and nonpregnant volunteers, there were consistent interruptions in the transmission of oxygen saturation data during the Valsalva maneuver. To determine the physiologic events associated with this monitoring interruption, occlusive venous impedance plethysmographs and pulse volume amplitude recordings were obtained in volunteers performing the Valsalva maneuver. A marked decrease in pulse volume amplitude was noted, which adversely affected the oximeter's ability to distinguish physiologic arterial pulsations from background noise. Each Valsalva maneuver was associated with abrupt and transient changes in peripheral vascular volumes, thus presenting the oximeter with a rapidly changing signal for analysis that violated predetermined software criteria for pulse uniformity and caused an interruption in data transmission. The authors conclude that the Valsalva maneuver interferes with the ability of pulse oximeter technology to provide useful oxygen saturation data.
在第二产程中，涉及连续瓦尔萨尔瓦动作的剧烈用力可能导致产妇低氧血症。脉搏血氧饱和度测定法已被用于评估分娩产妇的血氧饱和度，本研究旨在评估瓦尔萨尔瓦动作期间脉搏血氧仪（Nellcor）的性能。在孕妇和非孕志愿者中，瓦尔萨尔瓦动作期间血氧饱和度数据的传输均出现了持续中断。为了确定与这种监测中断相关的生理事件，在进行瓦尔萨尔瓦动作的志愿者中获取了闭塞性静脉阻抗体积描记图和脉搏容积振幅记录。发现脉搏容积振幅明显降低，这对血氧仪区分生理性动脉搏动与背景噪声的能力产生了不利影响。每次瓦尔萨尔瓦动作都与外周血管容积的突然和短暂变化相关，从而给血氧仪提供了一个快速变化的信号以供分析，这违反了预定的脉搏均匀性软件标准，并导致数据传输中断。作者得出结论，瓦尔萨尔瓦动作会干扰脉搏血氧仪技术提供有用血氧饱和度数据的能力。
